Understanding Guitar Electronics
This article explains how to visualize the path of the audio signal from your guitars pickups to your guitars amplifier.
How Guitar Electronics Work
Both the black and orange wire in the diagram to the left are representations of the wires inside your guitar and guitar cable. In every guitar cable there is a hot and ground wire. Simply put, if the signal from the pickups goes to the amp through the hot wire it will make sound. If the signal is sent to the ground wire before the amp then it will not make any sound at all. The whole idea of guitar wiring is to control how the guitar pickups signal gets to the amp. The guitar pickups signal is a lot like water in the way that it will always travel the path of the least resistance so if a connection is ever made between hot and ground wires, the signal wants to go to ground and no signal is heard.
Here is an example of the signal from the pickups being directed to the ground wire. The nail is metal so it will allow the signal to pass to the ground (the nail represents a wire). In this example there would be no sound coming from the amplifier because the signal from the guitar pickups is all going to ground. If you were to replace the nail with a simple on/off switch then you would have a primative volume control that can either be on or off.
It is far more practical to have a volume control rather than just a volume on/off switch. So, rather than just having an on/off switch we can replace it with something that will allow you to control how much of the pickups signal goes to the hot wire or the ground wire, a volume control. The way a volume control (potentiometer) works is by routing the signal to the ground wire or to the hot wire. It does this by resistance. Imagine a water slide above a pool with water rushing down it. The water is the signal from your guitar pickups. The water only goes down the slide (the hot wire) because it does not have a more direct path to the ground (ground wire). If you were to cut a hole in the slide a lot of water would fall to the ground through that hole because that is the most direct path to the ground. If you were then to make the hole in the slide much bigger then a lot more of the water would fall straight to the ground. Now imagine that the size of the hole is controlled by a valve. This is essentially what a volume potentiometer is. It allows you to guide the electricity to the destination of your choosing. It does this the same way the valve did in the water slide example. If the valve is completely closed the water can not go anywhere but down the slide. If the potentiometer knob is at ten then there is too much resistance for the signal to go to ground and so it goes to the hot wire. See how to wire a guitar volume control.
So now lets take a look at how capacitors can be used to control the tone of a guitar. Here we have a capacitor bridging the gap between the hot and ground wires. Rather than redirect the whole pickup signal to ground, the capacitor will direct different frequencies to either hot or ground when wired like this. The capacitor allows the high frequencies to escape to ground so they are not heard. The frequencies that are redirected to ground are dependent on which value capacitor is used. Hear an example of how different valued capacitors sound in the same guitar.
Just like with the potentiometer as a volume control, the potentiometer can also be used to direct how much signal goes to ground through a capacitor. The idea is that you wire the capacitor to the potentiometer in such a way that the high frequencies in the signal travel the path of least resistance to ground when the tone control is at 10 but are not allowed to go to ground when the tone control is at 0. See how to wire a guitar tone control.